The present invention relates to the storage of energy producing material for subsequent use, and, more particularly, relates to the utilization of a tunnel structure as an integral part of a liquefied propane or butane storage system.
Optimal use of propane or butane storage traditionally includes buying the material xe2x80x9coff seasonxe2x80x9d and using it in xe2x80x9cpeak seasonxe2x80x9d. Other techniques for storing propane or butane include storing them directly within underground leached salt caverns, within impervious mined caverns deep underground, or in tank structures that are designed specifically to hold liquefied propane or butane either at ambient temperature or in a slightly refrigerated state and may be above ground. Several tanks containing propane or butane at ambient temperature may be manifolded together in a storage facility to effectively act as a single storage unit. The facilities for all of the above provide for putting the fluid, propane or butane, into the storage medium, and for removal of the fluid when required.
Liquefied propane or butane may be stored in multiple 30,000 to 60,000 gallon steel tanks located above ground and supported by concrete piers. Large volume storage has been accomplished in leached salt caverns, in mined caverns within impervious rock strata deep under the surface of the ground or in large refrigerated tanks located above ground.
It is believed that there is no economically viable way of storing very large volumes of propane or butane at ambient temperature in a manner that allows the propane or butane to be accessed at ground level. In contrast, only by refrigerated storage can very large volumes of propane or butane currently be stored at ground level in a single location.
An exemplary fluid storage facility of the present invention includes an arrangement for transferring liquefied propane or butane from a supply source or at least one delivery vehicle to at least one pumping station via at least one weighing station, the pumping station transferring the liquefied propane or butane to at least one storage vessel. The at least one storage vessel is secured within a newly constructed tunnel or one that has been abandoned as a railroad tunnel, a highway tunnel and/or an aqueduct tunnel. The tunnel passes through the earth and includes an entrance at both ends, each of which is directly connected and directly accessible at ground level, and is configured to contain the at least one storage vessel for the storage of the liquefied propane or butane.
In an exemplary embodiment of the above exemplary fluid storage facility, the at least one storage vessel includes a plurality of storage vessels manifolded together to act as a single storage unit.
In an exemplary embodiment of the above fluid storage facility, first and second gas tight end walls are included at each end of the tunnel configured to seal the tunnel. The first and second end walls include attached sealed chambers, each chamber having two gas tight sealed access doors allowing entrance first into the corresponding chamber and then into the tunnel.
In an exemplary embodiment of the above fluid storage facility, the tunnel is filled with a mixture of air and an inert gas at a pressure slightly higher than atmospheric preventing combustion. According to a particular implementation, the inert gas may include nitrogen.
An exemplary embodiment of the above fluid storage facility includes a first pipeline coupled to the pumping station and to the at least one storage vessel for filling the at least one storage vessel, a second pipeline coupled to the pumping station and to the at least one storage vessel for removing liquid from the at least one storage vessel, a third pipeline coupled to the pumping station and to the at least one storage vessel for transporting any gas that is released through over pressure valves on the at least one storage vessel, and a fourth pipeline coupled to the pumping station and configured to provide for introduction of the inert gas into the tunnel. The first, second, third and fourth pipelines may pass through at least one of the gas tight end walls of the tunnel.
An exemplary method of providing a fluid storage facility having an entrance at both ends, each of which is directly connected and directly accessible at ground level, includes renovating a tunnel previously constructed as a transportation tunnel (such as a railroad or highway tunnel) or as an aqueduct to act as an integral storage system component for containing at least one storage vessel of an ambient temperature energy producing fluid. The renovated tunnel includes gas tight end wall chambers positioned at each end of the tunnel, each chamber having gas tight sealed access doors. The exemplary method also includes providing access for maintenance in the tunnel via the gas tight sealed access doors and providing access for at least one of an addition and a removal of storage tanks through an end wall of the tunnel.